Patent US5078087A successfully refreshed from Google Patents.
US5078087A
Expired / Lapsed
US
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Development apparatus
Assignee: Xerox Corp
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Filing: 1991-03-11
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Granted: 1992-01-07
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Expires: 2011-03-11
Abstract
Abstract An electrophotographic printing machine in which an electrostatic latent image is recorded on a photoconductive surface. One portion of the latent image is a discharged area with the other portion of the latent image being a charged area. The discharged image area is developed with toner particles of a first color and polarity by a first developer unit. No greater than 2% by volume of these toner particles have a diameter greater than about 20 microns. The first developer unit generates a weak magnetic field in the development zone and a strong magnetic field at the entrance and exit of the development zone. A second developer unit develops the charged image area with toner of a second color and polarity. The colors of the toners are different from one another.
Inventors
- 👤 Larry G. Hogestyn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:45
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0921; G03G13/00; G03G13/01; G03G13/013; G03G15/01; G03G15/0105; G03G15/0121
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
115 words
A printing machine of the type having a latent image recorded on a moving charge retentive surface, wherein the improvement includes: first means for developing, in a first development zone, a first portion of the latent image with toner particles of a first polarity, said first developing means having a distribution of toner particles wherein no greater than 2% by volume is coarse toner particles; and second means for developing, in a second development zone, a second portion of the latent image with toner particles of a second polarity, opposite to the first polarity, said second developing means being positioned after said first developing means in the direction of movement of the charge retentive surface.
Claim 2
Dependent Claim
115 words
A printing machine of the type having a latent image recorded on a moving charge retentive surface, wherein the improvement includes: first means for developing, in a first development zone, a first portion of the latent image with toner particles of a first polarity, said first developing means having a distribution of toner particles wherein no greater than 2% by volume is coarse toner particles; and second means for developing, in a second development zone, a second portion of the latent image with toner particles of a second polarity, opposite to the first polarity, said second developing means being positioned after said first developing means in the direction of movement of the charge retentive surface.
Claim 3
Dependent Claim
20 words
A printing machine according to claim 1, wherein the coarse toner particles have a diameter of at least 20 microns.
Claim 4
Dependent Claim
24 words
A printing machine according to claim 2, wherein the median diameter of the toner particles of said first developing means is about 13 microns.
Claim 5
Dependent Claim
41 words
A printing machine according to claim 3, wherein said first developing means comprises first magnetic means generating a weak magnetic field in the first development zone and a strong magnetic field at the entrance and exit of the first development zone.
Claim 6
Dependent Claim
31 words
A printing machine according to claim 4, wherein: the first portion of the latent image is a discharged area; and the second portion of the latent image is a charged area.
Claim 7
Dependent Claim
25 words
A printing machine according to claim 5, wherein said second means includes second magnetic means generating a weak magnetic field in the second development zone.
Claim 8
Dependent Claim
64 words
A printing machine according to claim 6, wherein: said first developing means develops the first portion of the latent image with toner particles of a first color to form a first visible image; and said second developing means develops the second portion of the latent image with toner particles of a second color different from the first color to form a second visible image.
Claim 9
Dependent Claim
31 words
A printing machine according to claim 7, further including means for transferring the first visible image and the second visible image substantially simultaneously from the charge retentive surface to a sheet.
Claim 10
Dependent Claim
123 words
An electrophotographic printing machine of the type having an electrostatic latent image recorded on a moving photoconductive member, wherein the improvement includes: first means for developing, in a first development zone, a first portion of the latent image with toner particles of a first polarity, said first developing means having a distribution of toner particles wherein no greater than 2% by volume of the toner particles have a diameter greater than about 20 microns; and second means for developing, in a second development zone, a second portion of the latent image with toner particles of a second polarity, opposite to the first polarity, said second developing means being positioned after said first developing means in the direction of movement of the photoconductive member.
Claim 11
Dependent Claim
123 words
An electrophotographic printing machine of the type having an electrostatic latent image recorded on a moving photoconductive member, wherein the improvement includes: first means for developing, in a first development zone, a first portion of the latent image with toner particles of a first polarity, said first developing means having a distribution of toner particles wherein no greater than 2% by volume of the toner particles have a diameter greater than about 20 microns; and second means for developing, in a second development zone, a second portion of the latent image with toner particles of a second polarity, opposite to the first polarity, said second developing means being positioned after said first developing means in the direction of movement of the photoconductive member.
Claim 12
Dependent Claim
24 words
A printing machine according to claim 9, wherein the median diameter of the toner particles of said first developing means is about 13 microns.
Claim 13
Dependent Claim
41 words
A printing machine according to claim 10, wherein said first developing means comprises first magnetic means generating a weak magnetic field in the first development zone and a strong magnetic field at the entrance and exit of the first development zone.
Claim 14
Dependent Claim
31 words
A printing machine according to claim 11, wherein: the first portion of the latent image is a discharged area; and the second portion of the latent image is a charged area.
Claim 15
Dependent Claim
25 words
A printing machine according to claim 12, wherein said second means includes second magnetic means generating a weak magnetic field in the second development zone.
Claim 16
Dependent Claim
62 words
A printing machine according to claim 13, wherein: said first developing means develops the first portion of the latent image with toner of a first color to form a first visible image; and said second developing means develops the second portion of the latent image with toner of a second color different from the first color to form a second visible image.
Claim 17
Dependent Claim
30 words
A printing machine according to claim 14, further including means for transferring the first visible image and the second visible image substantially simultaneously from the photoconductive member to a sheet.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-06 | 1995-07-08 | 1996-01-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-06 | 1999-07-08 | 2000-01-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-06 | 2003-07-08 | 2004-01-07 | $7700.00 | Window Closed / Lapsed |